The maximum compliance constrained SIMP subproblems were solved using a primal-dual augmented Lagrangian method [1]}. The inequality constraints were relaxed resulting in a box constrained max-min primal-dual problem. A projected gradient descent algorithm was used for the primal and dual problems with a backtracking line search. The maximum step size of the line search was initialized to 1 and adapted to be 1.5 the step size of the previous line search for both the primal and dual problems. A total of 10 dual iterations were used with a maximum of 50 primal iterations per dual iteration. The IPOPT termination criteria above was also used here. To regularize the scale of the problem, the compliance constraints were divided by the maximum compliance at the full ground mesh design. A trust region of 0.1 was used. An initial quadratic penalty coefficient of 0.1 was used with a growth factor of 3 in every dual iteration. Finally, an initial solution of 1.0 for all the primal variables and 1 for all the Lagrangian multipliers was used.
